I'm trying to create a map that has a all layers within a subject area having 0% transparency (full opaque), while features outside that area (defined by a polygon shapefile) having a reduced transparency of say 50%. The ideal result is a map that has a focus on a specific area, but also shows the surrounding area. I'm working with ArcMap 10.
Similar to this image:
I tried using the clip feature in the Data Frame properties but its not what I'm looking for.